Powdery Mildew problem?

Powdery mildew is a fungal disease that attacks a wide range of plants.

Main symptoms White, dusty coating on leaves, stems and flowers

Powdery mildew is spread by airborne spores that blow onto uninfected plants. The spores germinate on the plant and produce superficial patches (colonies) of greyish-white cottony mycelium and spores on the upper leaf surface, while yellow chlorotic spots appear on the underside of the leaf.